Tumor size is an independent risk predictor for metachronous colorectal cancer.

Takaharu Kato,Manuel Perucho,Yuta Muto,Toshiki Rikiyama,Sergio Alonso

doi:10.18632/oncotarget.7555

Abstract

Non-hereditary colorectal cancer (CRC) patients are at higher risk of developing independent metachronous CRC than cancer-naïve individuals, but the reason is unknown. We studied metachronous CRC risk factors among one thousand five Japanese CRC patients who underwent surgery for CRC.Relative hazard risk of clinical and pathological features was assessed by univariate and multivariate Cox's proportional hazard regression analysis. Observed metachronous CRC incidence was also compared with the expected cancer incidence of the general population in Japan.Twenty-seven metachronous CRCs developed in 24 patients (2.4%) during a follow-up period of 3,676 person-years. Multivariate analysis revealed two factors associated with a high metachronous CRC risk: synchronous CRC (HR = 6.13; p = 1.3×10−4) and tumor size ≥ 6.5 cm (HR = 4.34; p = 1×10−3). Patients with either synchronous or large solitary tumors exhibited a higher risk for metachronous CRC than patients with solitary small tumors (HR = 7.3; p = 4.3×10−6) and that the general Japanese population (SIR = 7.01; p = 3.5×10−9), while patients with solitary small tumors did not (SIR = 1.07; p = 0.8). If patients younger than 60 years were excluded, the observations remained unchanged, with tumor size becoming stronger predictor (HR = 5.67; p = 1.7×10−4) than the presence of synchronous CRC (HR = 5.34; p = 9.6×10−4).Our novel finding that primary tumor size is a strong independent risk factor for metachronous CRC increases the sensitivity of prediction more than twice the presence of synchronous CRC. Our data provides new insights to assess the risk for metachronous lesions that should improve the surveillance regimen for CRC.

Highlights

Colorectal cancer (CRC) is one of the most prevalent cancers in developed countries [1]
We retrospectively studied the incidence of metachronous CRC in a consecutive series of 1,022 Japanese CRC patients
Our results indicate that the presence of synchronous CRC and the primary tumor size ≥ 6.5 cm are strong and independent risk factors for metachronous CRC

Summary

Introduction

Colorectal cancer (CRC) is one of the most prevalent cancers in developed countries [1]. The incidence of CRC has increased lately two to four-fold in Asian countries [26]. Non-hereditary CRC patients are at higher risk to develop second independent, i.e. metachronous, malignancies [7]. Surveillance recommendations for CRC patients include a colonoscopy examination within the first year after surgery. Adherence to this recommendation ranges from 18-61% of the patients [9], and a significant proportion of metachronous CRC lesions remain undetected until the first post-operatory surveillance www.impactjournals.com/oncotarget colonoscopy, when they have already progressed to cancer. Identification of individuals at higher risk could improve patient post-operatory management by implementing a personalized, more effective surveillance plan and treatment. We report here that tumor size is a novel predictor for metachronous CRC development, that together with the presence of synchronous tumors increases the precision of risk assessment

Results

Discussion

Ethics statement

Conflicts of interest